Palm muting

Some things are so synonymous with the sound of heavy metal that it's easy to take them for granted. A palm-muted powerchord on a guitar is the foundation for heaviness.

Place the side of your picking hand (not actually the palm) across the strings you're playing close to the bridge - muting them - and then chug away! An accompanying grimace or sneer is nigh-on essential.

It has to be said that P is also for Pantera: The premier US metal band of the 1990s: groove, technical finesse and southern swagger. And that was just their six-stringer 'Dimebag' Darrell Abbott. RIP.